As a common extruder equipment, single screw extruder machine is used in the plastics processing industry. What is the principle and structure? The following is an analysis of the working principle of single screw extruder from the conveying section, compression section, and metering section of the extruder.
The single screw extruder machine is generally divided into three sections in terms of effective length. The effective lengths of the three sections are determined according to the screw diameter, pitch, and screw depth, which are generally divided into one-third of each.
1. The last thread of the material opening starts to be called the conveying section.
The material here is not required to be plasticized, but it must be preheated and compacted. In the past, the old extrusion theory believed that the material here was loose. Later, it was proved that the material here is actually a solid plug, which means that the material is a solid like a plug after being squeezed, so its function is to complete the delivery task.
2. The second section is called the compression section
At this time, the volume of the screw groove gradually becomes smaller, and the temperature must reach the degree of plasticization of the material. The compression produced here is from the third conveying section, and the compression is here to one. This is called the compression ratio of the screw - 3:1. There are also changes for other machines. The plasticized material enters the third stage.
3. The third section is the measurement section
The material here maintains the plasticizing temperature, just like a metering pump to accurately and quantitatively transport the melt material to supply the machine head. At this time, the temperature cannot be lower than the plasticizing temperature, generally slightly higher.
The single screw extruder machine is mainly used for extruding soft and hard polyvinyl chloride, polyethylene and other thermoplastic plastics. It can process a variety of plastic products, such as films, tubes, and plates, in conjunction with corresponding auxiliary machines (including molding heads), and it can also process the granulation.